The overall objective of our lung transplantation studies is to render this treatment modality more effective in the management of respiratory failure in man. The aims of the presently proposed research are threefold: first, the control of infection in the lung allograft recipient; second, the modification or abrogation of the immunologic rejection reaction following lung allografting; and third, the improved preservation of the lung before and during the transplant procedure. As a part of the infection control study, we propose to measure in dogs the functional capacity of peripheral blood polymorphonuclear leukocytes and of lung macrophages under a variety of experimental lung transplant conditions. The immunologic rejection study will include the characterization of the host's immunologic response to the lung allograft; chromium 51 tagged lymphocytes will be utilized in measuring cell mediated response and the production of humoral antibodies. Prolongation of lung allograft survival will be attempted by means of enhancement, effected by pre-transplant injection of lymphocytes from the spleen or the thymus of the prospective canine lung donor. Organ preservation studies already in progress will be extended in a search for an optimal method for prolonging the period of lung tolerance for cold ischemia. Since only bilateral lungs will be used in the latter studies, the ability of these organs to sustain the host will be the principal criterion for evaluating the efficacy of the preservation technique employed.